Comparison

Zero vs AllyFast

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Zero

This app tracks intermittent fasting and nutrition to help users achieve real body composition changes. It integrates fasting, protein intake, meals, hydration, and habits for a holistic approach to weight loss and metabolic health.

Highlights
  • Intermittent fasting timers and streaks
  • Smart meal logging with photo recognition
  • Personalized daily protein target tracking
  • Integrated fasting and protein tracking
  • Water and habit tracking
  • Science-based insights on fasting and nutrition
Features
Read full description

Zero is the all-in-one fasting tracker and nutrition app built for real results. Most fasting and weight loss apps stop at simply tracking fasts or calories. Zero connects the full picture — fasting, protein, meals, hydration, and habits — so you actually change your body composition, not just your eating schedule. Here’s how Zero helps you get there: • Track your intermittent fasting — Engage timers, streaks, and insights keep you stay motivated and consistent across your entire fasting journey. • Log meals the smart way — Skip the tedious manual meal entry routine. With Zero Plus, snap a photo and get instant macros, protein composition, and clarity on how effectively your meals support your goals. Your first meal logs are on us, so you can try it before you subscribe. • Hit your Protein Score — Zero Plus tracks a personalized daily protein target that adapts to your weight and goals. Better protein = better satiety, better muscle retention, better weight loss. Zero makes it automatic. • Complete the equation: Fasting + Protein — Most people fast or track meals. Zero brings them together so you lose weight, protect muscle, and avoid the pressure and guilt of traditional calorie trackers. • Stay hydrated to power your fasts — Water tracking with Zero Plus helps you maintain energy, reduce cravings, and support metabolic function throughout the day. • Build healthy habits that actually matter — Track movement, sleep, mood, and other daily pillars that reinforce your fasting and fueling routine. • Challenge yourself — Hit protein targets, maintain fasting streaks, and stay accountable with motivating challenges built around outcomes, not vanity metrics. • Learn the real science — Understand how fasting, protein, and hydration work together for sustainable weight loss and metabolic health — with insights from leading experts. • See measurable progress — Watch your streaks grow, your protein consistency rise, and your body composition improve with clean, insightful trend views. Whether you’re starting out or optimizing an existing routine, Zero gives you the structure, guidance, and clarity most apps miss. Zero is not a medical device and does not provide medical advice, diagnosis, or treatment. Always consult your doctor or qualified healthcare provider before making any changes to your diet, fasting routine, or health regimen. Zero is free to download, with fasting timers, streaks, weekly trends, expert articles, and challenges included. Zero Plus is an optional subscription that unlocks photo meal logging and your Protein Score, water tracking, custom fasts and saved presets, Fat-Burning Mode, the mood journal and daily habit insights, premium articles and Plus-only challenges, and monthly, yearly, and correlated charts. A free trial is available. Payment for Zero Plus will be charged to your Apple Account when you subscribe. Subscriptions automatically renew unless auto-renew is turned off at least 24 hours before the end of the current period. Manage your subscription in your Account Settings. Read more terms & conditions: Terms of use: https://www.zerolongevity.com/terms-of-use Privacy policy: https://www.zerolongevity.com/privacy-policy

About

AllyFast

This app offers a streamlined fasting timer with a clean, SwiftUI-based interface. It prioritizes user privacy with local data storage and provides science-based insights into fasting stages. Enjoy a clutter-free, ad-free experience with no subscriptions.

Highlights
  • SwiftUI fasting timer
  • Local data storage
  • No subscriptions or ads
  • Fasts up to 72 hours
  • Editable fasting history
  • Science-based fasting insights
Features
Read full description

AllyFast is a beautifully crafted intermittent fasting timer built with SwiftUI. Clean, lightweight, and privacy-first. Whether you follow 16:8, 18:6, 20:4, OMAD, or extended fasts, AllyFast keeps your fasting journey simple and focused. Why AllyFast? • No subscriptions. One-time $0.99. Yours forever. • 100% private. All data stays on your device. • No ads, no trackers, no accounts, no clutter. • Ultra lightweight at just 1.7 MB. Key Features • Beautiful fasting timer with smooth SwiftUI animations • Supports intermittent fasting plans: 12:12, 14:10, 16:8, 18:6, 20:4, OMAD • Extended fasts up to 72 hours • Editable fasting history with color-coded goal tracking • Science-based fasting stage insights (fed state, ketosis, autophagy, and more) • Unlimited local import and export of your fasting data • Polished for iOS 26 Liquid Glass • Full Dark Mode support Perfect Privacy Your fasting data never leaves your iPhone. No cloud sync, no servers, no tracking. Just you and your fast. Built for Everyone From beginners exploring their first 16:8 fast to experienced fasters tracking multi-day autophagy windows, AllyFast adapts to your goals without getting in the way. No cloud. No noise. Just fasting.

Screenshots

Zero4 screens
AllyFast4 screens

Verdict

The call

Zero and AllyFast both sit at 4.8 stars, but that hides the real split: 100% of AllyFast's written reviews are positive against 32% of Zero's. AllyFast also leads on in-app purchases (none vs 10). Zero's advantage is price (Free vs $0.99) and ratings volume (445K vs 22). On rating, ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Zero is free to download; AllyFast costs $0.99 up front. Zero sells 7 in-app purchases, starting at $9.99 per month. AllyFast asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

AllyFast holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: Zero has 445K ratings behind it against 22, so its average is the more settled of the two. Written reviews point the same way: 32% of Zero's written reviews are positive against 100% of AllyFast's.

UpkeepUpdate frequency

Zero ships an update every 2 weeks, AllyFast monthly. The most recent releases landed on November 4, 2026 and October 30, 2026 respectively.

Scorecard7 real differences · 4 level
Zero versus AllyFast: the parameters behind the verdict, then further details
ParameterZeroAllyFast
PriceFree — better$0.99
Rating4.8 (445K ratings)5.0 (22 ratings) — better
Positive reviews32.0% of reviews100.0% of reviews — better
Number of ratings445K — better22
Update frequencyEvery 2 weeks — betterMonthly
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemium — betterPaid
Best chart rank#102 — better—
DevicesiPhone, Apple WatchiPhone, iPad
Requires iOS17.0 — better18.2
Further details — not scored
Size195 MB2 MB
Age rating17+4+
DeveloperZero Longevity Science, Inc.Wonseok Lee

Customer experience

Zero

All ratings445,285 ratings
Positive96.3%
Neutral2.1%
Negative1.6%
Written reviews1,400 reviews
Positive32.0%
Neutral8.6%
Negative59.4%

AllyFast

All ratings18 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews6 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

Zero

Reported bugs

3 issues
  • Password reset problems
  • Inaccurate fasting time tracking
  • Inability to exit trial without subscribing

Requested features

6 requests
  • Custom fasting periods longer than 24 hours
  • Ability to edit fasting type and duration
  • Integration with more health/fitness apps
  • Water intake tracking
  • Personalized fasting recommendations
Show 1 more
  • Improved data visualization and analytics

AllyFast

Not enough reviews yet to summarise bugs or requests.

In-app purchases

7 purchases

Zero

Subscriptions7
  • Zero Plus Subscription2 variants$9.991 Month
  • Zero Plus Subscription7 Days trial$9.991 Month
  • Zero Plus Subscription7 Days trial2 variants$69.991 Year
Show 4 more
  • Zero Plus Subscription$69.991 Year
  • Zero Plus Subscription1 Year trial2 variants$69.991 Year
  • Zero Plus Subscription1 Month trial$69.991 Year
  • Zero Plus Subscription7 Days trial$89.991 Year
None

AllyFast

No in-app purchases

Questions

Is Zero free?
Zero is free to download, with in-app purchases available.
Is AllyFast free?
AllyFast costs $0.99, with no in-app purchases.
Which has better reviews, Zero or AllyFast?
AllyFast is rated higher. Zero averages 4.8 out of 5 from 445K ratings, while AllyFast averages 5.0 from 22 ratings.
Do Zero or AllyFast have ads?
Neither Zero nor AllyFast shows ads.
Which is updated more often, Zero or AllyFast?
Zero ships an update every 2 weeks, and AllyFast monthly. Most recently, Zero was updated on November 4, 2026 and AllyFast on October 30, 2026.

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